Hawaii is extremely environmentally conscious and has many programs to protect its land and waters. Thats why.
Showing an interest may help a tiny amount, but as Stole Your Nose said, most people that specialize don't do so in law school. You don't need to have taken every class in environmental law at school to eventually specialize in the practice. So if you (with an environmental law tilt to your resume) and someone with the same grades/qualifications but with local ties are competing for a job, that other person may very well beat you out.
So without local/family ties to the area, without being able to demonstrate that you are seriously committed to Hawaii as more than a good beach locale, you may very well have a difficult time. I'm not saying impossible, but it's going to be difficult (at least until you relocate there and take the HI bar; that shows serious commitment, I think).